The present invention relates to an inkjet printer and inkjet printing method, and more particularly to an inkjet printer and inkjet printing method for conducting edgeless printing on a printing medium by moving a printing head along a guide shaft and ejecting a pigment ink from the printing head.
Inkjet printers capable of conducting printing with a zero margin on the front, rear, left, and right edges of a printing medium were disclosed (for example, Japanese Patent Applications Laid-open Nos. H7-9712 and 8-169155). With those openly disclosed inkjet printers, the printing operation is executed by so setting the scanning range of a printing head, which is placed on a carriage, that it reaches the positions outside the left and right edges of the printing medium.
When printing is carried out with such an inkjet printer, as shown in FIG. 5(A), a printing paper 100 serving as a printing medium is transported in the auxiliary scanning direction shown by arrow A and when the front edge 100A of the printing paper 100 reaches a position below the printing head 101, the carriage (not shown in the figure) moves reciprocally along the main scanning direction shown by arrow B, an ink 102 is ejected from the printing head 101, and printing on the printing paper 100 is started.
At this time, in order to conduct printing so that the margin at the front edge 100A of the printing paper 100 is zero, the ink 102 is caused to overflow to the outside from the front edge 100A of the printing paper 100.
If a state shown in FIG. 5(B) is then assumed by transporting the printing paper 100 from the above-described position in the auxiliary scanning direction shown by arrow A, then in order to conduct printing so that the margin at the side edge 100B of the printing paper 100 is zero, the ink 102 is caused to overflow to the outside from the side edge 100B of the printing paper 100 by appropriately adjusting the reciprocal movement distance of the carriage in the main scanning direction shown by arrow B.
Furthermore, if a state shown in FIG. 5(C) is then assumed by transporting the printing paper 100 from the above-described position in the auxiliary scanning direction shown by arrow A, then in order to conduct printing so that the margin at the rear edge 100C of the printing paper 100 is zero, the ink 102 is caused to overflow to the outside from the rear edge 100C of the printing paper 100.
Here, the pigment ink 102 that overflowed from the front edge 100A, side edge 100B, or rear edge 100C of the printing paper 100 is absorbed by the platen 104 shown in FIG. 6. For example, Japanese Patent Application Laid-open No. H7-9712 discloses using a porous ceramic or the like as an ink absorbing body. When a pigment ink was used to conduct edgeless printing with such a configuration, in particular, under utilization conditions with increased room temperature, for example, in a warm season, moisture present in the pigment ink 102 that was ejected onto the platen rapidly evaporated and pigment precipitated.
As a result, as shown in FIG. 7, the pigment ink 102 sometimes could not be sufficiently absorbed by the platen 104 and, as shown in FIG. 8, the ink (pigment) 102 sometimes formed a deposit (sometimes referred to hereinbelow as “pile 105”) on the surface of the platen 104.
If such a pile 105 appears on the source of the platen 104, when printing is conducted on the next printing paper 100, the end surface of the printing paper 100 is brought into contact with the pile 105 and the end surface of the printing paper 100 is contaminated.
With the foregoing in view, it is an object of the present invention to provide an inkjet printer and inkjet printing method using a pigment ink, wherein the ink that overflowed to the outside from the edges of the printing medium can be fully absorbed by a platen.